Abdomen
Abdominal (adjective)
The posterior part of the adult body in arthropods, comprising ten segments in insects.

Achene
A small, dry, single-seeded fruit (q.v.) that does not split open.

Adventitious
Plants: Roots or buds arising from an unusual position on a stem.

Aerobic
Needing free oxygen or air to live/function/work. The opposite of anaerobic.

Anaerobic
See also: Aerobic
Not needing free oxygen or air to live/function/work. The opposite of aerobic.

Anamorph
(fungi)
The non-sexual form of fungi.

Angiosperm
Flowering plant producing a covered seed.

Anhydrobiosis
A state of suspended animation characterised by nearly complete loss of all water; organisms in anhydrobiotic condition will revive after rehydration.

Anion
An atom or molecule carrying one or more surplus electrons, and therefore having a negative charge.

Annual
Plants completing their lifecycle in one year or less. The plant dies after flowering or maturity.

Anther
Main male reproductive structure, in which pollen are formed and stored.

Anthesis
The period of flowering, from the opening of the flower-bud to the setting of the seed.

Anthracnose
Common name of plant diseases characterised by black lesions, usually sunken, caused by certain imperfect fungi that produce conidia in acervuli, e.g. Colletotrichum, Gloeosporium and some closely-related Sphaceloma spp.
It is recommended that the term be used only as the common name for diseases caused by Colletotrichum lindemuthianum on Phaseolus, C. coffeanum on coffee, and Gloeosporium limetticola on lime, Citrus aurantifolia. The disease of raspberry and loganberry caused by Elsinoë veneta is better known as 'cane spot'. (BSPP)

Apical dominance
The tendency for a plant's apical meristem to be more active than its lateral or axial meristems. It is particularly evident in young trees, and is due to production of auxins in the apical meristem.

Aril
A fleshy structure or skin on a seed used to attract ants or birds to disperse the seed

Berry
A type of simple fruit having a fleshy exocarp, mesocarp, and endocarp. Example: tomato.

Biological pest control
The use of organisms that do not compete with the crop to control populations of crop competitors.

Biparental
Having a male and female parent.

BSPP
British Society for Plant Pathology.

Bt
Insect-toxic bacterial protein (from Bacillus thuringiensis), produced by a gene that has been cloned and introduced into various crops to provide transgenic insect protection.

Boron (B)
Plant essential micronutrient, usually found in the soil in a borate anionic form.

Bud
A scion with one bud used in grafting.

Budding
A type of graft in which the scion is a bud.

Bulb
A type of modified subterranean storage stem/bud consisting of overlapping fleshy leaf bases or scales. Example: garlic and onions.

Calyx
Outermost floral whorl, consisting usually of modified leaves known as sepals.

Callus
Parenchymatous cell mass that forms over plant wounds and is commonly seen growing as white, undifferentiated cells from cultured plant cells or tissues.

Cambium
Cambium layer; Cambial
A thin layer of meristematic cells found between the wood and bark of woody plants. Often called the 'inner bark'. Every year the cambial cells divide to produce new cells on each side, the many large inner layers becoming wood cells or xylem, and the small outer layers becoming bast or phloem. Outside the bast, a small bark-cambium grows an outer layer of bark cells each year to form the protective bark (q.v.).

Canker
Plants: A sunken necrotic lesion of main root, stem or branch arising from disintegration of tissues outside the xylem cylinder, but sometimes limited in extent by host reactions which can result in more or less massive overgrowth of surrounding tissues; concentric zonation may indicate successive host responses to advancing infection. In a perennial canker, infection and host responses continue for more than one season. Because no new wood is formed under such cankers the lesions appear to penetrate deep into the wood: this is because continued growth outside the limits of the lesion tends to bury it. Infection normally continues to be restricted mainly to the bark tissues. A hold-over canker is one in which the pathogen survives the winter/dormant season and from which it may re-infect healthy tissues in the spring/growing season. A term particularly used of fireblight cankers caused by Erwinia amylovora. (BSPP)

Capitate
i. Antennae with enlarged terminal segments forming a knob.

ii. Head-like.

Cation exchange capacity (CEC)
The ability of a soil's colloids to attract and hold onto its cations. Soils high in humus and expanding clays tend to have the highest CECs.

Centre pivot
A sprinkler irrigation system consisting of a mobile line attached to a fixed central well, resulting in a cultivated field arranged within a circle.

Chlorosis
Partial or complete absence of normal green colour in plants, where the affected organs become yellow-green, yellow or white. The condition may result from reduction in size or number of chloroplasts, destruction of chlorophyll, or from a failure of synthesis of chlorophyll as in iron deficiency. Failure to produce chlorophyll can be the result of genetic factors (albinism) or chimaeral growth or growth of plants in darkness (etiolation). (BSPP)

Clean cultivation
The complete cultivation or removal of all plant residues from the soil surface.

Climacteric
Point in time when fruit can be harvested and still ripen to maximum quality.

Coleoptera
Insect order that includes beetles and weevils, which damage plants mainly by chewing plant parts. Examples of economically-important species: Rhinoceros beetle, longhorn beetle, bean weevil, cucumber beetle. The lady bird beetle (lady bug) is an important biological control organism for aphid infestations, particularly in greenhouses.

Colloid
Insoluble soil microparticles including clays and humus. These soil colloids have a net negative charge.

Complete flower
A flower having all four floral whorls: stamens, pistils, petals, and sepals.

Conidia
Conidium (singular)
Asexual spores produced on conidiophores other than sporangiospores and chlamydospores.

Corm
An enlarged, compressed, underground modified stem, often with scaly leaves.

Cornicle
Siphuncle
A tubular organ on the abdomen of an aphid, from which a waxy fluid is secreted as a pheromone when the insect is attacked.

Corolla
Second of the four floral whorls moving inward, containing the modified leaves known as petals.

CPPC
(Regional Plant Protection Organization)
Caribbean Plant Protection Commission

Crawler
The active first instar (q.v.) of a scale insect.

Crucifers
Plants of the mustard family (Brassicaceae). The term "crucifer" comes from the cross-shaped configuration of the four flower petals. Ex., broccoli, cabbage, canola, turnips.

Cucurbits
Plants of the cucumber/melon family (Cucurbitaceae). Ex., cantaloupe, cucumber, squash, watermelon, etc.

Culm
The stem of a monocotyledonous plant, e.g. grasses, cereals.

Cultivar
cv (abbreviation)

See also: Variety; Strain
i. 'An assemblage of cultivated individuals which is distinguished by any characters (morphological, physiological, cytological, chemical or others) significant for the purposes of agriculture, forestry or horticulture and which, when reproduced (sexually or asexually), retains its distinguishing features'. (Cult. Code, Art. 5). (BSPP)

ii. Variety.

iii. Strain, e.g. barley 'Balder'. A cultivar may be a clone (Solanum tuberosum 'King Edward VII') or a line (Tbriticum aestivum 'Marquis'). Plant pathologists should use this useful term in the sense of the Code, e.g. for cultivars (varieties) of the cultivated mushroom. Use of the term in the sense of R. H. Stover (Canadian Journal of Botany 37: 245-255, 1959) 'a distinct group of isolates that have some common morphological or physiological characteristics but which may consist of one or more clones or races', e.g. Fusarium oxysporum (cultivar) 'Inodoratum' (clone) B, is to be deprecated. (BSPP)

Cultivation
The turning of surface soil to prepare a seedbed, aerate, and/or eliminate weeds.

Cuticle
The outer protective envelope of any living organism. In the case of mammals or arthropods, the alternative names 'skin' or 'integument' are often used. However, cuticle is always used with regard to green plants. Plant cuticle is a macromolecular structure of predominantly paraffinic composition over-lying cellulose and pectin.

Cyme
An inflorescence in which the central terminal flower comes to perfection first.

Damping off
Collapse and death of seedling plants resulting from the development of a stem lesion at soil level. This is a growers term, apparently deriving from the damp conditions among seedlings crowded in a box, which favour the attack and spread of such pathogens as Pythium spp. Pre-emergence damping-off is the death of seedlings, as a result of disease, before they have emerged above the surface of the soil or other medium. (BSPP)

Defoliation
The removal of leaves or portions of leaves from a plant.

Dehisce
Dehiscence (variety form) Dehiscent (variety form) Dehiscing (variety form)
To split open along a natural line, especially when associated with discharge of contents, as in the opening of seedpods or the freeing of pollen by the anther.

Dieback
Die-back (variety form)
Necrosis of a shoot, starting at the apex and progressing downwards towards the main stem. (BSPP)

Dioecious
Plant species having male (staminate) and female (pistillate) flowers on separate plants. Examples:sago palm, asparagus and some fig varieties

Diptera
Insect order consisting of true flies. Important plant pests include the cabbage root maggot, Oriental fruit fly and Cucurbit fruit fly.

Dormancy
The period of plant growth inactivity. May be in the seed or in the whole plant.

Drupe
The fruit of certain plants, having a thin exocarp, fleshy or leathery mesocarp, and a hard, stony endocarp. Examples: mangoes and rambutan.

Ectoparasitoid
A parasitoid that lives on the external surface of its host, feeding on it and killing it in the process

Elytron
Elytra (plural)
One of a pair of hard upper wings in Coleoptera and Dermaptera.

Endoparasitoid
A parasitoid that lives in another organism, feeding on it and killing it in the process.

Epiphyte
A plant which grows on the surface of another organism without causing any harm to that organism.

EPPO
OEPP (variety form) (Regional Plant Protection Organization)
European and Mediterranean Plant Protection Organization

Ethylene
A plant growth-regulating gas, naturally produced in ripening fruit as well as other parts of the plant, responsible for promoting ripening and involved in abscission and other plant processes.

Etiolation
See also: Chlorosis
Internode extension and the lack of green colour that result from growth of a plant in insufficient light or complete darkness. (BSPP)

Exudate
A substance that oozes out from animal or plant pores.

Exuvium
Exuvia (plural) Exuviae (plural)
The cast skin of arthropods after moulting/ecdysis.

F1 hybrid
A plant derived from a sexual cross between two homozygous but different parents.

Facultative parasite
See also: Parasite
One able to live as a saprophyte and to be cultured on laboratory media (not obligate). (BSPP)

Fallowing
Practice of leaving a field unplanted during a growing season, usually to conserve moisture and nutrients.

Family
Plant taxonomic category consisting of a group of related subfamilies, tribes (as in grasses), or genera. Examples: Fabaceae (legume family), Poaceae (grass family), Solanaceae (nightshade family).

Fibrous root
A threadlike root, as in grasses.

Field capacity
The point at which all excess gravitational water has drained from a soil.

Flagellum
Microbiology: A whip-like organ of motility found on bacteria, flagellates and zoospores.
Entomology: That part of an insect's antenna beyond the pedicel.

Frass
The waste of wood-boring insects and caterpillars. Contains a high proportion of plant fragments.

Fruiting body
A fungous structure that contains or bears spores, e.g. a mushroom.

Genus
Generic (adjective) Genera (plural)
A taxonomic grouping of organisms having common characteristics distinct from those of other genera, usually containing one or more species and being one of a series of genera constituting a taxonomic family.

Girdling
A phloem-disruption method of inducing reproductive bud development. All of the cambium except for small patches are severed in a ring around the stem, thus causing a localised increase in the carbohydrate/nitrogen ratio in the upper portion of the plant. This method is often used in seedless grape production.

Glabrous
Hairless or bald. The opposite of pubescent or hirsute.

Grafting
Graftage
The union of two different plant parts to create a single new plant.

Gregarious
Tending to move in or form a group with others of the same kind.

Gummosis
Emission of gum from a tissue or organ; production of gum may be external, constituting a characteristic symptom, as in cherry bacterial canker (Pseudomonas mors-prunorum) and cucumber gummosis (Cladosporium cucumerinum), or it may be internal, resulting in the filling of lysigenous cavities in xylem or phloem, or occlusion of vessels as a response to wounding or infection by vascular pathogens. (BSPP)

Haemolymph
Hemolymph (variety form)
Lymph-like nutritive fluid in insects and other arthropods which is the equivalent of blood in vertebrates.

Hardening
Gradual exposure of nursery plants to warmer temperatures, drier conditions, increased light, or reduced fertility in preparation for transplanting in the field.

Haustorium
Haustoria (plural)
A simple or complex structure formed by an interaction between a branch of a fungal hypha and a host cell into which it has penetrated without causing lethal injury, generally assumed to provide a means by which a fungus absorbs nutrients from the host cells. (BSPP) Haustoria are also found in parasitic plants which grow on trees, where they perform the same function.

Herb
Herbaceous (adjective)
i. A plant that contains little woody tissue above ground and which usually dies back to ground level during the dormant season.

ii. A term also applied to aromatic plants used to flavour dishes of food.

Herbicide
Chemical that destroys plant life. Categories include narrow vs. broad spectrum; systemic or translocated vs. contact; persistent vs. non-persistent; and preplant, preemergence, and postemergence types.

Hermaphrodite
Bisexual. In a flowering plant, having both stamens and carpels in the same flower; in an animal, producing both male and female gametes.

Homoptera
Insect order consisting of phloem-sucking insects, including whiteflies and aphids. Economically important species include the green citrus aphid, melon aphid and whiteflies.

Honeydew
Liquid waste with high sugar content discharged from the anus of some Homoptera and settling on surrounding vegetation as thin, sticky droplets.

Horizon
A given soil layer in a soil profile. Horizons are designated as A, B, C, or D, with the A horizon being the surface layer, usually.

Host
i. An organism harbouring a parasite (BMS). A living organism harbouring another organism or virus dependent on it for existence (APS). The individuals of a species which are capable of harbouring a parasite, even though a particular individual or population of that species may not at the time be parasitized, can also be described as hosts; however, in these circumstances it is preferable to refer to the organism as a potential host. The term is used commonly in preference to suscept (q.v.) to denote an organism harbouring a pathogen. Nevertheless, it must be stated that the conceptual parallel of 'host and parasite' is 'suscept and pathogen'. (BSPP)

ii. The plant on which a pest feeds, i.e. the food- or hostplant.

Host range
The series of plants that a particular pathogen can infect or parasitise.

Humus
Dark brown, decomposed, colloidal organic matter found in soils. Humus usually has a beneficial effect on aeration and soil structure due to its ability to flocculate, or aggregate, multivalent cations.

Hyaline
Transparent. Used when referring to a transparent or translucent spot devoid of scales on the wing of a butterfly or moth, or the whole wing of some insects, e.g. Odonata, Hymenoptera.

Hybrid vigour
Heterosis
The superior phenotypic characteristics of an F1 hybrid when compared with its two distinct, homozygous parents.

Hyperparasite
Hyperparasitism
See also: Parasite
A parasite or parasitoid attacking another parasite within a host organism. For example, a hyperparasite of a fruitfly attacking a parasite within the fruitfly larva or pupa.

Hypha
Hyphae (plural)
A single thread of fungal mycelium.

Inbreeding depression
The successive loss of population vigour with each generation of selfing of an F1 hybrid. It is often seen in outcrossing, vegetatively-propagated, and/or heterozygous autotetraploid plants.

Ingest
To eat or swallow.

Instar
Larval instar (synonym) Stadium (synonym)
A stage in the development of a larva between two moults; a stadium.

Intercropping
The planting of two different crops together in the same field.

Internode
Plants: The stem structure between two nodes or joints.

IPM
IPM Integrated pest management, a strategy for controlling crop pests using a combination of tactics, including crop management practices, pesticides, biological competitors, etc.

Larva
Larval (adjective) Larvae (plural) Worm (synonym)
i. The growing, worm-like stage of insects with a complete metamorphosis; the caterpillar, 'worm', maggot or grub.

ii. The newly hatched six-legged stage of mites and ticks.

Layering
Root induction on stem tissue in order to eventually sever the tissue for propagating a new individual plant.

Leaching
Gravitational movement of water, dissolved, and colloidal substances from the surface or upper horizons to lower horizons in a soil.

Lepidoptera
Order of chewing insects that have a caterpillar or worm stage and a flying adult stage. Examples: Diamondback moth, armyworm, codling moth, rambutan fruit borer, citrus leafminer.

Lesion
i. A localized area of diseased or disordered tissue. (BSPP)

ii. Any break in the epidermis of a plant or animal caused by a disease or disorder.

Legumes
Plants of the pea family (Fabaceae) that form characteristic elongated seed pods and fix atmospheric nitrogen through symbiotic interaction with soil bacteria of the genera Rhizobium and Bradyrhizobium. Ex., beans, peas, peanuts, soybeans, tamarind, etc.

Lenticel
A white/brown, corky, raised 'breathing' pore on a woody shoot.

Locule
Plants: The cavity of an anther which contains the pollen, or the chamber of an ovary which contains the ovules.
Fungi: A cavity in the stroma containing asci.

Locus
Specific place on a chromosome or genetic map where a gene and its alleles are found.

Lodging
When plants fall over and lie flat on the soil surface, especially cereal grain crops, often due to wind, hail, and/or excessive stem growth.